Apparatus and method for separating materials

ABSTRACT

A material separator for separating at least two different materials of differing densities and/or sizes of particles. The material separator generally includes a tank containing a flocculent, a circulation system for circulating flocculent within the tank and a pair of conveyors for moving two different materials out of the tank. The tank may include an upper chamber and a lower chamber. At least a portion of each of the conveyors is located in the upper chamber to catch materials fed into the flocculent. Each of the conveyors may include a mesh belt that permits the flocculent to flow through the conveyor. The tank may include a clean out valve that permits fines and other debris accumulated within the upper chamber to pass into the lower chamber. The flocculent circulation assembly may include a nozzle that can be constructed in various configurations to create flows of flocculent of various velocities and trajectories. In one embodiment, the lower chamber includes a drag line assembly that removes fines and other accumulated debris from the lower chamber.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus and method for separatingmaterials for reclamation, disposal and other purposes.

There are a wide variety of industrial applications where mixedmaterials are generated. For example, demolition debris may include amix of wood, concrete and various metals. In another example, a varietyof industrial manufacturing processes yield waste that includes mixedmaterials. Further, mixed materials may be result from mining, landclearing or other extraction methods. In many applications, mixedmaterials simply accumulate as useless waste, and may ultimately need tobe moved to a landfill or other waste storage site at significant cost.

Many of these mixed materials include at least one material that, ifseparated efficiently, would be suitable for reuse, recycling or otherreclamation. In some applications all of the mixed materials may besubject to reuse, recycling or other reclamation once sorted, andtherefore would not leave significant waste once sorted. Althoughseparation is desirable, the apparatus and methods currently availablefor separating materials can be labor intensive and costly. In an effortto provide an alternative to manual sorting, an apparatus for sortingdemolition debris is shown in U.S. Pat. No. 4,813,518, which issued onMar. 21, 1989 to one of the inventors of the present invention. Althougha marked improvement over preexisting apparatus and methods for sortingdemolition debris, the apparatus of the '518 patent is not ideal for allpotential sorting applications. For example, the apparatus is relativelylarge and not easily moved from location-to-location. Further, theapparatus is primarily intended for use in sorting demolition debris andis therefore tailored specifically for that application. The apparatusis not designed with the adjustability to permit a single machine to bereadily tuned for use in other applications. Also, fines and othersolids accumulate in the tank, thereby requiring periodic cleaning ofthe tank. Despite the benefits of the apparatus of the '518 patent,various industries could benefit from a highly effective separator withincreased efficiency and improved performance. Further, an apparatusthat is more easily adapted for use in different applications would bebeneficial.

SUMMARY OF THE INVENTION

The aforementioned problems are overcome by the present inventionwherein a material separator is provided with a tank-over-tank design.The tank includes an internal divider that separates the tank into upperand lower chambers. In one embodiment, the internal divider includes avalve that controls the flow of flocculent from the upper chamber to thelower chamber. The valve may be a butterfly valve that can be pivoted topermit more or less flocculent to flow from the upper chamber into thelower chamber.

In one embodiment, the material separator includes a first materialconveyor having a mesh belt. The mesh belt permits the flocculent toflow and drain through the belt as the carried materials. The materialseparator may include a second material conveyor having a mesh belt. Thematerial separator may be provided with additional conveyors inapplications where more than two materials are to be separated. Ifadditional conveyors are included, the additional conveyors may alsoinclude mesh belt. If desired, the mesh conveyors may include an airknife that expels a strong flow of air through the belt to clean off anyfines or other small debris that may be trapped in the mesh belt.

In another embodiment, the material separator includes a clean out valvedisposed in the internal divider to permit waste material that hasfallen below the conveyors to be flushed into the lower chamber. In thisembodiment, the internal divider may be angled and the clean out valvemay be disposed at the lowermost end of the internal divider where finesand other solids are most likely to accumulate.

In yet another embodiment, the material separator includes a drag linedisposed within the lower chamber. The drag line includes a plurality ofwipers that are dragged across the floor of the lower chamber to removefines and other solids that have accumulated in the lower chamber. Thedrag line dumps the solids from the tank through an opening in the lowerchamber.

In another embodiment, the material separator includes a flocculentcirculation system having a nozzle that expels a broad and uniformdischarge of flocculent across the upper chamber. The nozzle expelsflocculent into a skirt arrangement that causes essentially all of theflocculent to flow onto the belts (and not around the sides of) of theconveyors.

The material separator of one embodiment includes retractable wheelsthat facilitate movement of the material separator from one location toanother. The wheels may be pivotally mounted to the tank and operated byconventional pneumatics. For example, each wheel may include a separateair bag that can be inflated to extend the wheels for movement of thetank and deflated to retract the wheels.

The present invention provides a highly efficient material separatorthat provides improved material separation for a wide variety ofmaterials. In applications which include a tank-over-tank design, thecirculation of flocculent can be carefully controlled to, among otherthings, facilitate improved separation. In applications which includeone or more mesh conveyor belts, the mesh facilitates separation bypermitting flocculent to easily pass through the belts. In applicationswhich include an air knife, the life of the mesh belts can bedramatically improved. The accumulation of fines and other debris canhave a dramatic impact on the performance of the system and on the lifeof the components. The clean out valve permits accumulated material tobe expelled from upper chamber into the lower chamber. The drag linepermits fines, debris and other solids to be expelled from the lowerchamber, thereby eliminating the need to manually clean the lowerchamber. The nozzle and skirt arrangement improve the performance of thematerial separator by directing an even and uniform flow of flocculentonto the conveyors. The retractable wheels permit the tank to be easilymoved, as desired.

These and other objects, advantages, and features of the invention willbe readily understood and appreciated by reference to the detaileddescription of the preferred embodiment and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a material separator in accordance withan embodiment of the present invention.

FIG. 2 is a right side elevational view of the material separator.

FIG. 3 is a left side elevational view of the material separator.

FIG. 4 is a top plan view of the material separator.

FIG. 5 a is a sectional view of the material separator taken along lineV-V of FIG. 4.

FIG. 5 b is a sectional view of the material separator taken along lineV-V of FIG. 4 with portions removed to more clearly show the flotationtank.

FIG. 6 is an enlarged sectional view of area VI of FIG. 3 with portionsremoved to show the first material conveyor clean out valve.

FIG. 7 is an enlarged section view of area VII of FIG. 3 with portionsremoved to show the butterfly valve.

FIG. 8 is an enlarged perspective view of area VIII of FIG. 3 with thefirst conveyor removed.

FIG. 9 is a perspective view of a portion of the material separator withportions removed to show the nozzle.

FIG. 10 is a perspective view of the first material conveyor.

FIG. 11 is a top plan view of the first material conveyor.

FIG. 12 is a sectional view of the first material conveyor taken alongline XII-XII of FIG. 4 showing the belt in the upper and lower channels.

FIG. 13 a is an enlarged view of a portion of the material separatorshowing the upper tank clean out valve.

FIG. 13 b is an exploded perspective view of the upper tank clean outvalve assembly.

FIG. 14 is a perspective view of the second material conveyor.

FIG. 15 is a sectional view of the first material conveyor taken alongline XV-XV of FIG. 2 showing the air knife assembly disposed between theupper and lower runs of the belt.

FIG. 16 is a perspective view of the drag line assembly with portionsremoved.

FIG. 17 is a bottom perspective view of the material separator withportions removed to show the wheel and frame assembly.

FIG. 18 is a side elevational view of the material separator showing thewheels in the raised position.

FIG. 19 is a perspective view of the feed assembly with the feedassembly conveyor belt removed.

FIG. 20 is a perspective view of the impeller assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

I. Overview

A material separator 10 in accordance with the present invention isshown in FIG. 1 and generally designed 10. The material separator 10generally includes a feed assembly 12 for feeding a mixture of materialsinto the separator 10, a flotation tank 14 containing a flocculent 26, aflocculent circulation assembly 16 for circulating the flocculent withinthe tank 14, and two or more material conveyors 18 for moving theseparated materials from the tank 14 (See also FIG. 5 a). In operation,the material separator 10 functions to separate the different materialsin the mixture of materials through the use of a circulating flocculent26 and spaced apart material conveyors 18. Separation is initiated whenmaterial 24 to be separated is deposited into the feed assembly 12. Thefeed assembly 12 gradually distributes the material 24 to be separatedinto the flocculent 26 contained within the flotation tank 14. Althoughnumerous complex factors contribute the separation of the materials, thematerials that have the lower specific gravity (material A) are moved bythe circulating flocculent onto the first conveyor 30. The firstconveyor 30 carries material A over the far wall 36 of the flotationtank 14 where material A is then deposited into a suitable collectioncontainer or another collection means. The material with a greaterspecific gravity (material B), descends to the bottom of the upperchamber 42 of the flotation tank 14 and onto the second conveyor 44. Thesecond conveyor 44, which is located below the first conveyor 30,carries material B over the far wall 36 of the flotation tank 14 wherematerial B is then deposited into a suitable collection container oranother collection means separate from material A.

The present invention is described in connection with illustrationsshowing a single embodiment of the present invention. The presentinvention is well suited for use in separating a wide variety ofmaterials, including demolition debris, and can be adapted to correspondwith the density/specific gravity/particle size of the materials to besorted. In general, the present invention operates on the principle thatmaterials of greater density, greater specific gravity or greaterparticle size will drop more quickly than materials entering the tank oflower density, lower specific gravity or smaller particle size withinthe flocculent. As described in more detail below, the present inventionincludes a variety of features that facilitate its tuning for use indiscrete applications with various materials to be separated. Forexample, by varying the characteristics of the flocculent (e.g. density,specific gravity, viscosity and temperature), the speed at which theflocculent is circulated within the system, the angle at which theflocculent is expelled from the nozzle, the speed at which the materialsto be separated are introduced into the flotation tank, thecharacteristics of the material conveyor belts (e.g. openness of the ofthe mesh), the speed of the material conveyor belts, the distribution ofthe material to be separated as it enters the flotation tank and therate at which the flocculent flows from the upper chamber to the lowerchamber, the material separator can be tuned to separate a wide varietyof materials. The present invention is described in connection with anembodiment for separating two materials. The present invention is alsosuitable for use in separating three or more materials provided that thematerials are sufficiently dissimilar in density, specific gravityand/or particle size.

II. Feed Assembly

As noted above, the feed assembly 12 moves the materials to be separatedinto the tank 14. The materials may be pre-screened as necessary toremove unwanted materials, such as excessively large items or particlesof sand and dirt. A variety of pre-screening apparatus, such asvibratory screens, are known and therefore will not be described herein.As perhaps best shown in FIGS. 1 and 19, the feed assembly generallyincludes a hopper 46 for receiving the materials to be sorted, conveyor50 for moving the materials into the tank 14 and a weighted flipper 56for limiting and distributing the materials evenly over the conveyor 50.The separation process begins when material 24 to be separated isdeposited into the feed assembly hopper 46. The feed assembly hopper 46has four, funneled side walls 48 that channel material onto the feedassembly conveyor 50. The feed assembly conveyor 50 is a generallyconventional adjustable-speed conveyor that has a belt 52 made of rubberor any other suitable material and an adjustable speed drive motor 51.In the depicted embodiment, the feed assembly conveyor belt 52 issupported by a framework of longitudinal and transverse support members54, but the belt 52 could also be supported by rollers or any othersuitable means.

Material 24 to be separated is limited and distributed evenly over thefeed assembly conveyor 50 as the material 24 to be separated passes outof the hopper 46 by the operation of a hinged, weighted flipper 56. Thisflipper 56 is mounted in an opening 58 of the front wall 60 of thehopper 46 above the feed assembly conveyor 50. When material 24 isdeposited into the hopper 46 and onto the feed assembly conveyor 50, theconveyor 50 moves the material 24 to be separated against the hinged,weighted flipper 56. The motion of the feed assembly conveyor 50 causesthe material 24 to be separated within the hopper 46 to generate a forceagainst the hinged flipper 56. This force causes the flipper 56 to swingout in the direction of the flotation tank 14. The weight of the flipper56 limits the amount of material that moves beneath and causes thematerial to be spread out over the conveyor 50. Once past the flipper56, the feed assembly conveyor 50 then carries the material 24 to beseparated over the near wall 62 of the flotation tank 14 and drops thematerial 24 to be separated into the flocculent 26 at the near end ofthe flotation tank 14 (See FIG. 5 a).

The rate at which the material 24 is deposited into the flotation tank14 from the feed assembly 12 will affect the separation characteristicsof the material separator 10, and the rate may be tuned to enhance theperformance of the system. This rate can be controlled in many ways. Forexample, the rate at which the feed assembly conveyor belt 52 travelscan be adjusted. In this embodiment, the conveyor belt 52 is driven by avariable-speed electric motor 51. The rate of belt 52 can be easilyadjusted by varying the speed of the motor 51. Also, the weight 66 (SeeFIG. 4) placed on the flipper 56 can be increased or decreased tocontrol the amount and distribution of material 24 on the feed assemblyconveyor 50 passing out of the hopper 46. The height of the feedassembly conveyor 50 above the flotation tank 14 can also be adjusted tocontrol the performance of the separation system 10. The higher theheight of the conveyor 50 over the flotation tank 14, the greater thespeed the material 24 has as the material 24 enters the flow 32 offlocculent 26 released from the nozzle 34, which is described in moredetail below. This speed has an effect on the accuracy and overallperformance of the separation system 10.

Although the feed assembly 12 is expected to be desirable in mostapplications, it may be possible to eliminate the feed assembly 12 insome applications. In such applications, the materials to be separatedare introduced into the tank 14 by other mechanisms. For example, thematerials may be dumped directly into the tank 14 by a bucket loader orother machinery or may be moved into the tank 14 by an externalconveyor.

III. Flotation Tank

As summarized above, separation of the materials occurs in the flotationtank 14, which contains a circulating flow of flocculent 26. In oneembodiment, the flotation tank 14 is a quadrangular shaped open topcontainer. As perhaps best shown in FIGS. 5 a and 5 b, the depictedembodiment generally includes a flat bottom 68, a near end wall 62, aleft side wall 70, a right side wall 72 and far end wall 36. The far endtank wall 36 is sloped away from the near end (e.g. end toward the feedassembly) of the flotation tank 14. In one embodiment, the tank 14includes a drag line assembly 76, which is described in more detailbelow (See FIG. 16). In this embodiment, the far end wall 36 of theflotation tank 14 defines a drag line outlet 74 through which the dragline assembly 76 expels fines and other debris dredged from the tank 14(See FIG. 5 b). In the illustrated embodiment, the drag line outlet 74is a slot spanning the width of the far end tank wall 36.

In one embodiment, a partition 78 divides the flotation tank 14 into anupper chamber 42 and a lower chamber 88. The partition 78 functions,among other things, to facilitate flocculent 26 circulation as well asaid in maintaining a clean tank 14 to prevent premature component wear.The partition 78 slopes upward from the near end of the flotation tank14 toward the far end of the flotation tank 14. At the near end of thetank 14, a cleanout valve 82 is installed in the partition 78 (See FIGS.13 a and 13 b). This valve 82 (described below) can be opened to allowdebris that has collected at the bottom 84 of the second conveyor 44 inthe upper chamber 42 to be released into the lower chamber 88 of theflotation tank 14 preventing wear or damage to the second conveyor 44caused by debris build up. A butterfly valve 86 is also installed in thepartition 78 approximately two thirds of the distance back from the nearend of the flotation tank 14 (See FIG. 7). The drag line outlet 74 islocated in the lower chamber 88 of the flotation tank 14 where the dragline 76 operates.

IV. Flocculent Circulation Assembly

A flocculent 26 is circulated through the tank 14 to facilitateseparation of the mixed materials (See FIG. 5 a). The flocculent 26 alsoaids in cleaning the tank 14 and material conveyors 18. In theillustrated embodiment, the material separator 10 includes a flocculentcirculation assembly 16 that draws flocculent 26 from the lower chamber88 and expels it into the upper chamber 42 (See FIGS. 3, 5 a and 5 b).The flocculent 26 may be any fluid material having the desired specificgravity and other flow characteristics. For example, the flocculent 26may be selected to have a specific gravity that is greater than thespecific gravity of the one of the materials to be sorted and less thanthat of another of the materials to be sorted. In many applications,water may be used as the flocculent 26 if its specific gravity providesadequate separation performance. If desired, one or more additives maybe introduced into the water (or other flocculent) to provide it withthe desired characteristics. For example, a surfactant or other agentaffecting surface tension can be added to the flocculent. The flocculent26 is supplied to the material separator 10 by actuating a flocculentsupply valve. For example, the circulation system 16 may include a floatvalve 92 in the lower chamber 88 of the flotation tank 14 to control theflow of additional flocculent 26 into the tank 14. In one embodiment,this float valve 92 includes a conventional supply control valve that ismechanically actuated by a float 93 located in the lower chamber-similarto the float valves used in a standard household toilet. The float valve92 may be mounted within a water inlet 91 in the side wall 70 of thetank 14 (See FIG. 5 b). Essentially any float valve with the desiredfunctionality may be substituted for the described float valve. Forexample, the float valve may alternatively be electromechanical having afloat that provides an electrical signal to the control valve whenadditional flocculent is needed. The flocculent supply valve need not bea float valve and may alternatively be any of a variety of other typesof valves. For example, the valve may be manually turned on by anoperator when it is determined that additional flocculent 26 isrequired.

Circulation of the flocculent 26 within the flotation tank 14 is drivenby an impeller assembly 94 located in front 96 of the near end 64 of theflotation tank 14. Referring now to FIG. 20, the impeller assembly 94generally includes an impeller blade assembly 110 that is mounted to ashaft 98 and that is driven by a variable speed motor 100. In oneembodiment, the shaft 98 is supported at its uppermost end 102 by abearing 104 and in its mid section 106 by another bearing 108. Theimpeller blade assembly 110 is located at the bottom 112 of the shaft 98submerged in the flocculent 26 within the pump housing weldment 114. Thenumber and location of the bearings may, however, vary. For example, inanother embodiment, the second bearing 108 is located beneath theimpeller blade assembly 110 at the bottom 112 of the shaft 98. In thisalternative embodiment, the second bearing 108 is located inside thepump housing weldment 114 submerged in the flocculent 26. Accordingly,it may be desired for the second bearing 108 to be a marine bearing. Theformerly described embodiment of the impeller assembly 94 potentiallyprovides advantages in component life over the latter embodiment becausethe second bearing 108 is not submerged in flocculent 26.

The impeller assembly 94 drives the flocculent 26 up a pipe assembly 116located in front 118 of the impeller assembly 94 and connected to thepump housing weldment 114. The pipe assembly 116 travels verticallyupward from the front 118 of the pump housing weldment 114 and thenmakes an angle 120 into the top 122 of the near end wall 62 of theflotation tank 14. In the depicted embodiment, this angle 120 isapproximately 75 degrees, but the angle 120 may be altered to optimizeseparation performance of the system 10.

A nozzle 34 is attached to the pipe assembly inlet 122 on the near wall62 of the flotation tank 14 where the pipe assembly 116 connects to theflotation tank 14 (See FIGS. 5 b and 9). One embodiment of this nozzle34 is an elongated ellipse that causes a flow 32 of flocculent 26 to bedirected across the width of the flotation tank 14. In anotherembodiment, the nozzle 34 size and shape may be altered to produce aflow 32 of flocculent 26 with the desired thickness and speed for theparticular separation application. Skirt walls 124 start on both sidesof the nozzle 34 and continue up to connect with the sides 126 of thefirst conveyor 30 (See FIGS. 1 and 10). These skirt walls 124 direct theprimary flow 32 of flocculent 26 and guide material A up and onto thefirst conveyor 30. The skirt walls 124 also extend down from the nozzle34 to join the edges of the diverter plate 39 (described in more detailbelow) and extend to the end of the second conveyor 44 to guide heaviermaterial onto the second conveyor 44. In this embodiment, the skirtwalls 124 and diverter plate 39 are removably mounted within the tank 14so that they can be replaced as they become worn or otherwise damaged.

As noted above, the illustrated embodiment includes a butterfly valve 86located in the partition 78 of the flotation tank 14 about two thirds ofthe way back from the near end 64 of the flotation tank 14 (See FIGS. 5a, 5 b and 7). The butterfly valve 86 controls the flow of flocculent 26from the upper chamber 42 to the lower chamber 88 of the flotation tank14. Adjusting the butterfly valve 86 will affect how much flocculent 26is reserved in the upper tank 42. The butterfly valve 86 may includemanual or automated controls. In operation, the flow 128 of flocculent26 through the butterfly valve 86 is balanced with the flow 32 offlocculent 26 through the nozzle 34 generated by the impeller assembly94 to maintain the desired level of flocculent 26 in the upper chamber42 of the tank 14. The butterfly valve 86 is installed in a slot 130defined by the partition 78. In this embodiment, the slot 130substantially spans the width of the flotation tank. A flat, rectangularplate 132 fills this slot 130 when the butterfly valve 86 is completelyclosed. The rectangular plate 132 is attached to a threaded rod 134 by aconventional linkage. The threaded rod 134 passes through a mountingbracket 136 located on the outside of the flotation tank 14. When therod 134 is moved, the linkage causes the plate 132 to pivot open orclosed allowing more or less flocculent 26 to flow 128 from the upperchamber 42 of the flotation tank 14 to the lower chamber 88. The morethe plate 132 of the butterfly valve 86 pivots open, the more flocculent26 will flow from the upper chamber 42 to the lower chamber 88. A pairof nuts 135 are fitted over the rod 13 on opposite sides of the bracket136. The nuts 135 can be tightened against the bracket 136 to secure therod (and hence the butterfly valve 86) in the desired position. Thebutterfly valve 86 may be adjusted while the separation system 10 isoperating to provide the desired balance for optimal performance of thesystem 10.

V. Material Conveyors

In the illustrated embodiment, the material separator 10 includes twomaterial conveyors 18 that convey the separated materials from the tank14 (See FIGS. 1, 2 and 5 a). In one embodiment, the separator 10includes a first conveyor 30 spaced vertically above a second conveyor44. Both conveyors 18 are located in the upper chamber 42 of theflotation tank 14 and begin at near end 64 of the flotation tank 14 andextend over the far wall 36 of the flotation tank 14. The first conveyor30 is suspended above the second conveyor 44 using suspension brackets140. The first conveyor 30 and second conveyor 44 are staggered with thefirst conveyor 30 starting farther back from the near wall 62 of theflotation tank 14. This permits materials that drop through theflocculent 26 quicker to fall onto the second conveyor 44. The firstconveyor 30 also extends farther beyond the flotation tank 14 than thesecond conveyor 44 so that material A is moved to a different locationthan material B.

In operation, the first conveyor 30 of this embodiment collects materialA that has a lower specific gravity than material B or that is otherwisecarried by the flocculent 26 to the first conveyor 30. Material A floatsor sinks relatively slowly after being dumped into the flocculent 26 bythe feed assembly conveyor 50. The flow 32 of flocculent 26 from thenozzle 34 guides the material A onto the first conveyor 30. The firstconveyor 30 carries the material A over the far wall 36 of the flotationtank and deposits material A into a container or another suitablecollection means. In this embodiment, the second conveyor 44 collectsmaterial B, which has a greater specific density than material A orotherwise falls to the second conveyor. When material B is dropped fromthe feed assembly conveyor 50 into the flotation tank 14, the material Bis not carried as far by the flocculent 26, but instead sinks to thebottom 40 of the upper chamber 42 quickly enough to avoid the firstconveyor 30. Material B lands on the second conveyor 44 and is carriedover the far wall 36 of the flotation tank 14 where the material B isdeposited into a container or some other appropriate collection means.As perhaps best shown in FIGS. 5 a and 8, a diverter plate 39 is mountedat bottom of the near end 40 of the flotation tank 14 at an angle infront of the second conveyor 44 to guide the material B onto the secondconveyor 44. The diverter plate 39 defines an opening 61 through whichextends the nozzle 34. Because the diverter plate 39 is mounted at anangle, it may include supports 59 that extend substantially horizontallyfrom the diverter plate 39 to engage end wall 62 (See FIG. 5 a). Thesupports 59 may engage a bracket 63 mounted on the inside of end wall 62(See FIG. 9). At least one buffer flight 45 may be installed on thediverter plate 39 to decelerate material B before the material impactsthe second conveyor 44 preventing premature wear on the second conveyor44. The diverter plate 39 may also includes a plurality of rubber skirts53 that extend from the bottom end and overlap the second conveyor 44.The diverter plate 39 may further include a pair of angle brackets 55extending along opposite sides of the buffer flights 45 to interconnectwith the skirt walls 124, for example, by bolts. The diverter plate 39may be removably mounted within the tank 14 so that it can be readilyreplaced if it becomes worn or damaged. To facilitate replacement, thediverter plate 39 may include a centrally located lift ring 47.

In the illustrated embodiment, the first conveyor 30 generally includesa belt 168, a drive roller 350, a variable speed drive motor 352, anidler roller 354 and a plurality of belt supports 172 (See FIGS. 10 and11). The belt 168 is a mesh belt and may be constructed from polyestermesh manufactured by GKD-USA or any other suitable material. The belt168 is made of mesh to permit the flocculent 26 to flow through the belt170 providing enhanced performance. Although the belt 168 is made ofmesh in the illustrated embodiment, it may alternatively be manufacturedfrom other perforated materials in some applications. The drive roller350 and idler roller 354 are generally conventional and therefore willnot be described in detail. The drive motor 352 may be a variable speedmotor to permit adjustment of the speed of the first conveyor 30. Thebelt 168 is supported and rides upon an arrangement of conventionallongitudinal belt supports 172. The belt supports 172 can be constructedof UHMW polyethylene or any other suitable materials.

To prevent debris from binding up in the idler roller 354, the firstconveyor 30 of the illustrated embodiment includes a shroud 370 thatshields the idler roller 354 from debris. The shroud 370 includes apivotal lower panel 144 that can be dropped down to release any materialthat may accumulate within the shroud 370. FIG. 6 shows the panel 144 inthe closed position in solid lines and in the open position in phantomlines. The lower panel 144 is a flat, rectangular piece of material 148spanning the width of the first conveyor 30. One edge of the lower panel144 is pivotally mounted to the underside of the shroud 370 beneath theidler roller 354 by axle 154. The opposite edge of the lower panel 144is operatively connected to a handle 156 by a conventional linkage. Whenthe handle 156 is opened, the lower panel 144 is free to pivotdownwardly about axle 154 to release the debris. When the handle isclosed, the lower panel 144 is lifted back up into a positionenshrouding the idler roller 354. In this embodiment, the lower panel144 opens toward the far end of the tank 14 so that debris is releasedin the direction of travel of the second conveyor 44. This reduces thepossibility of the second conveyor 44 causing the debris to flow back upinto the workings of the first conveyor 142.

In one embodiment, the first conveyor mesh belt 168 travels up and outof the tank 14 on upper rails 182 and travels down and back into thetank 14 in lower channels 184 (See FIG. 12). The upper rails 182 andlower channels 184 shepherd the belt 168 and prevent debris from flowingaround the belt 168 into the inner workings of the conveyor 30, forexample, into the idler roller 354. The upper rails 182 extend along oneach side 186 of the frame 188 of the conveyor 30 from a point neardrive roller 350 to a point near idler roller 354. The upper rails 182may, however, extend along less of the conveyor 30, as desired. Theupper rails 182 are generally L-shaped and each defines a shelf 183 thatreceives the corresponding edge of the top mesh belt surface 192 as thebelt 168 travels up and out of the tank 14. A rubber skirt 380 ismounted above the belt 168. The rubber skirt 380 overlays thelongitudinal edges of the belt 168, preferably along the entire lengthof the first conveyor 30, to prevent debris from flowing around thelongitudinal sides of the belt 168. The lower channels 184 extend alongon each side 186 of the frame 188 of the conveyor 30 throughapproximately the lower one third of the first conveyor 30. They may,however, extend along more or less of the conveyor 30, as desired. Thelower channels 184 each define a generally U-shaped slot 185 thatreceives the corresponding edge of the bottom mesh belt surface 193 asthe belt 168 travels down back into the tank 14. The upper rails 182 andlower channels 184 may be manufactured from UHMW polyethylene or othersuitable materials. UHMW polyethylene is desirable in some applicationsbecause it is wear resistant and provides a relatively low frictionsurface against which the belt 168 can ride.

In the illustrated embodiment, the second conveyor 44 is somewhatsimilar to the first conveyor 30 and generally includes a belt 162, adrive roller 360, a variable speed drive motor 362, an idler roller 362and a plurality of belt support rollers 174 (See FIG. 14). As with belt168, the belt 162 of the second conveyor 44 may be manufactured frommesh or another perforated material. The drive roller 360 and idlerroller 362 are generally conventional and therefore will not bedescribed in detail. The drive motor 362 may be a variable speed motorto permit adjustment of the speed of the second conveyor 44. The belt168 is supported and rides upon an arrangement of conventional rollers174. The rollers 174 are better able to withstand the impact and supportthe weight of material B than the belt supports 172 described above inconnection with the first conveyor 30. The rollers 174 are arranged sothat the second conveyor 44 is concave. The concavity of the secondconveyor 44 assists in retaining material B on the second conveyor 44 asit is conveyed out of the flotation tank 14. The first several rollers174 supporting the second conveyor belt 162 may be impact rollers 176that are able to withstand the impact of dense material B as it dropsfrom the feed assembly conveyor 50 through the flocculent 26. Thesubsequent rollers 178 on the second conveyor 44 may be standard metalrollers 178. All of the conveyors 18 may be constructed in any way thatprovides the required performance of the separation system 10 including,but not limited to, steel rollers, impact rollers, frame supports, meshbelts, rubber belts, and flights. The second conveyor 44 may alsoinclude skirting extending along a portion of the conveyor 44. Theskirting may include rigid upper skirting 175 and flexible lowerskirting 177. The rigid upper skirting 175 may be manufactured fromsheet metal and may be mounted to opposite sides of the conveyor 44. Theflexible lower skirting 177 may be manufactured from rubber and may bemounted to the lower end of the rigid skirting 175. The flexible lowerskirting 177 may be configured to overlap opposite longitudinal edges ofthe belt 162.

To aid in bringing material B up and out of the flotation tank 14,flights 160 may be added on the second conveyor belt 162 (See FIG. 8).These flights 160 provide traction for the material B to be moved up bythe second conveyor 162 without rolling back down again. The flights 160may be spaced apart any appropriate distance on the second conveyor belt162 and may be attached to the second conveyor belt 162 using anysuitable mechanism. However, consideration should be given to thepotential degradation to the life of the belt that may be caused by theselected attachment mechanism. One suitable method for attaching theflights 160 to the belt 162 is to sandwich the belt 162 between theflight 160 and a corresponding cleat (not shown). The flight 160 andcleat are interconnected by a plurality of fasteners, such as bolts 164,that extend through the belt 162. The flight 160 and cleat cooperativelydistribute the attendant forces across the belt 162 over the width ofthe flight 160 to reduce the likelihood of damage to the belt 162. Thearea of the belt 162 where the cleat is attached to the flight 160 maybe fortified with epoxy or another suitable material. The epoxyreinforces the belt 162 in the attachment region reducing the likelihoodof fraying or other damage to the belt 162. For example, the epoxyentraps and holds any belt strands 166 that may have been sheared orotherwise damaged when the cleat 164 was attached.

In one embodiment, the conveyors 18 are equipped with air knives 202 forcleaning purposes (See FIGS. 2 and 15). Debris can become lodged in theholes of the mesh belts 162, 168 during standard operation of theseparation system 10. The air knife 202 projects a blast of air throughthe mesh belts 162, 168 to dislodge any debris stuck in the belts. Theair knife system 202 generally includes a blower 206, a pair of airtubes 214 and a network of the air supply lines 220. The blower 206 isattached to the outside of a side wall 210 of the flotation tank 14. Aseparate air tube 214 is mounted adjacent to each mesh belt 162, 168. Inthe illustrated embodiment, the air tubes 214 are located between theupper and lower surfaces of the corresponding belt 162, 168 (See FIG.15). Each air tube 214 defines a series of small holes (not shown) whichare capable of releasing pressurized air A onto the belts 162, 168. Forexample, each air tube 214 may define a plurality of staggered slots(not shown) that cooperatively direct pressurized air A across the fullsurface of the corresponding belt 162, 168. Each air tubes 214 ispositioned adjacent to the bottom surface 218 of the corresponding meshbelt 162, 168 with the holes pointing downward through the bottomsurface 218 of the mesh belt 162, 168. Air lines 220 run from the blower206 to the air tubes 214. Valves 217 may be positioned along the airlines 220 to control the amount of air supplied to each air tube 214. Inoperation, the blower 206 supplies pressurized air A to the air tubes214 via the air lines 220. The pressurized air A is expelled from theair tubes 214 through the arrangement of holes. The pressurized aircauses debris stuck in the mesh belts 162, 168 to be blasted free fromthe belts and fall downward and away from the separation system 10. Inone embodiment, a guide (not shown) may be attached to the conveyor 18to direct the debris to the desired location.

In one embodiment, a spray bar (not shown) for spraying down sortedmaterials with flocculent 26 may be installed on the first 30 and second44 conveyors.

VI. Cleaning Mechanisms

One embodiment includes several mechanisms 20 that aid in maintainingthe system 10 free of debris and extending the component life of theseparation system 10. These mechanisms 20 include a drag line assembly76 in the lower chamber 88 of the flotation tank 14 (See FIG. 16), acleanout valve 82 separating the upper 42 and lower 88 chambers of theflotation tank 14 (See FIGS. 13 a and 13 b), a water tight hatch (notshown) for manual cleaning and repair, and a drain valve 230 fordraining the flotation tank 14 (See FIG. 1), as well as, the previouslydescribed shroud lower floor 144 (See FIG. 6) and air knives 202 (SeeFIG. 2).

The drag line assembly 76 is located in the lower chamber 88 of theflotation tank 14 to dredge the floor of the lower chamber 88. The dragline assembly 76 collects and disposes of debris accumulated in thelower chamber 88 to prevent the debris from being re-circulated throughthe impeller assembly 94 causing wear or damage to the impeller assembly94 or material conveyors 18. As perhaps best shown in FIG. 16, the dragline assembly 76 generally includes a plurality of wipers 252 that arecarried on a pair of chains 248. For ease of illustration, the chains248 are shown in FIG. 16 as solid strips, but it should be recognizedthat the chains 248 are generally conventional chains. The chains 248and wipers 252 are driven around a drive assembly 234 and two idlerassemblies 236 by a motor 253. The drive assembly 234 is located in theuppermost portion of the far end 238 of the lower chamber 88 of theflotation tank 14 and generally includes a pair of chain drive gears 400mounted toward opposite ends of an axle 402. The axle 402 is operativelyconnected to the motor 253 so that operation of the motor causesrotation of the axle 402 and consequently the chain drive gears 400. Thefirst idler assembly 240 is located at the bottom 242 of the far end 246of the flotation tank 14, and the second idler assembly 244 is locatedat the bottom 242 of the near end 244 of the flotation tank 14. The twoidler assemblies 240 and 244 generally include a pair of gears 404mounted toward opposite ends of an axle 406. The axles 406 are rotatablymounted within the tank 14, for example, to the tank walls. The twochains 248 are operatively engaged with drive assembly 234 and the idlerassemblies 236. The wipers 252 are attached between these chains 248 atthe desired interval. The wipers 252 consist of a flat metal base 254connected to the chains 248 at each of the base ends 254 with a blade258 of UHMW polyethylene or other appropriate material connected to thebase 254. The bottom of the flotation tank 242 is dredged by the blade258 to prevent wear on the metal base 254. However, the wiper base 254may be constructed of any materials and in any way that providesacceptable functionality.

As perhaps best shown in FIGS. 13 a and 13 b, the cleanout valve 82 islocated on the partition 78 at the near end 64 of the flotation tank 14.The cleanout valve 82 is opened to allow small debris that has collectedat the bottom 252 of the upper chamber 42 of the flotation tank 14 to bereleased into the lower chamber 88 where the drag line 76 can remove thedebris from the flotation tank 14. The cleanout valve 82 generallyincludes a rectangular shaped piece 260 that overlaps a gap 262 betweenthe partition 78 and the near end wall 62 of the flotation tank 14. Therectangular piece 260 is attached to a rod 264 with a handle 266. Therod 264 may be supported within the tank 14 upon bearings 257. Thehandle 266 may be of essentially any type. However, in the illustratedembodiment, the handle 256 is a conventional locking handle having aspring handle 271 and a locking plate 273 that permits the valve 82 tobe locked in the desired position. When the handle 266 is turned, therod 264 to turns causing the rectangular piece 260 to pivot open, makingan opening 268 between the upper 42 and lower 88 chambers of theflotation tank 14. Debris that has collected on top 270 of therectangular piece of the cleanout valve 260 in the upper chamber 42 thenfalls to the lower chamber 88 of the flotation tank 14 where the debrisis disposed of by the drag line 76. The cleanout valve 82 limits thewear on the second conveyor 44 caused by debris settling into itsmechanisms 272. The cleanout valve 82 also limits the amount of manualcleaning required of the separation system 10 by moving debris to alocation where the drag line 76 can to dispose of it.

A water tight hatch (not shown) is located in end wall or side wall ofthe flotation tank 14 in the lower chamber 88 of the tank 14. The hatchprovides accessibility to the lower chamber 88 should the need everarise for manual cleaning or to service any components of the separationsystem 10. A drain valve 230 is also located in the lower chamber 88 ofthe flotation tank 14 to completely drain the system 10 when necessaryfor service or cleaning or when moving the material separator 10.

VII. Wheel and Frame Assembly

In one embodiment, the flotation tank 14 is supported by a steel frame22 made up of transverse and longitudinal cross members 274, 276 (SeeFIG. 17). In the depicted embodiment, seven frame members transverse 276beneath the tank 14 and three longitudinal frame members 278 span thelength of the tank 14. However, the material separator 10 may includeany support structure that provides an adequate foundation for theflotation tank 14.

In one embodiment, a towing hitch 280 and wheels 294 may be added to theflotation tank 14 to increase portability of the separation system 10(See FIG. 1). The hitch 280 in the depicted design is located on thenear end 64 of the flotation tank 14 connected to the frame supportmembers 22 on the underside of the flotation tank 14. The hitch 280 isconnected at the bottom near corners of the flotation tank 14 and comestogether at a point some distance in front of the near end 64 of theflotation tank 14. At the point where the hitch members come together288 means 290 to connect the hitch 280 to a trailoring vehicle isattached.

Four wheel assemblies 282 are placed on the tank 14 in the depictedembodiment (See FIGS. 2 and 3). The wheel assemblies 282 have thecapability to be raised or lowered through use of heavy duty air bags292 (See FIGS. 3 and 18). This allows the wheels 294 to be raised sothat the tank 14 rests directly on the ground when filled withflocculent 26; this adds stability to the separation system 10 andminimizes stress on the wheels 294. When the wheels 294 are lowered, thepressurized air bags 292 provide cushioning to the separation systemduring transport. Air pressure is provided for the air bags 292 by anair tank 296 mounted on the flotation tank 14. In one embodiment, theair tank 296 pressurizes a portion of the tubular frame 276, 278 that isadjacent to the air bags 292. The airbags 292 are then connected to thepressurized frame segment 276, 278 using air hoses (not shown) or someother connection means. In this way, the tubular frame 276, 278functions as the air lines for supplying pressurized air to the air bags292. Alternatively, conventional air hoses (not shown) or some otherconnection means may be run directly from the air tank 296 to the airbags 292. The airbags 292 are connected to a pivot bracket 302 which isconnected to the wheel assembly 282. When the airbags 292 are inflated,the pivot bracket 302 is rotated downward causing the wheels 294 to belowered. When air pressure is released from the airbags 292, the pivotbracket 302 rotates in the opposite direction and the wheels 294 aremoved upward. Movement of the wheels 294 can be seen by comparing FIG. 3(lowered for travel) with FIG. 18 (raised for operation).

To facilitate maintenance and operation of the separation system 10,catwalk platforms 304 may be placed over the wheel assemblies 282 onboth sides 210 of the flotation tank 14 in one embodiment (See FIGS. 1and 18). A ladder 306 hangs from the catwalk platform 304 for entranceto the platform 304, and a guardrail 308 is located around the platform304 for safety of those on the platform. The catwalk platforms 304 allowoperators to view the separation device 10 while the separation device10 is running and to make any necessary adjustments for optimalperformance of the system 10.

The above description is that of a preferred embodiment of theinvention. Various alterations and changes can be made without departingfrom the spirit and broader aspects of the invention as defined in theappended claims, which are to be interpreted in accordance with theprinciples of patent law including the doctrine of equivalents. Anyreference to claim elements in the singular, for example, using thearticles “a,” “an,” “the” or “said,” is not to be construed as limitingthe element to the singular.

1. An apparatus for separating materials comprising: a tank containing aflocculent, said tank having an upper chamber and lower chamber, saidupper chamber being in fluid communication with said lower chamber,whereby flocculent may flow from said upper chamber to said lowerchamber; a first material conveyor disposed in said upper chamber, saidfirst material conveyor having at least an end disposed in saidflocculent, said conveyor being operable to convey materials from saidtank, said first material conveyor includes a perforated belt; a secondmaterial conveyor, said second material conveyor having at least an enddisposed in said flocculent, said second material conveyor beingoperable to convey materials from said tank; and a flocculentcirculation system interconnecting said upper chamber and said lowerchamber, said flocculent circulation system being operable to moveflocculent from said lower chamber to said upper chamber; furtherincluding a valve interposed between said upper chamber and said lowerchamber, said valve being operable to vary a rate of flow of flocculentfrom said upper chamber to said lower chamber; said tank includes adivider wall extending between said upper chamber and said lowerchamber, and wherein said valve is disposed within said divider wall,and further including a clean out valve disposed within said dividerwall.
 2. The apparatus of claim 1 wherein said divider wall is inclinedhaving an upper end and a lower end, said clean out valve being disposedtoward said lower end.
 3. An apparatus for separating materialscomprising: a tank; a flocculent contained within said tank; aflocculent circulation system for circulating said flocculent within thetank; and a conveyor for removing materials from said tank, saidconveyor having at least a lower end disposed within said flocculent,said conveyor having a perforated belt, whereby said flocculent iscapable of passing through said belt; further comprising a secondmaterial conveyor having at least a lower end disposed within saidflocculent, said second material conveyor having a perforated belt, saidfirst material conveyor disposed vertically above said second materialconveyor, said first material conveyor extends substantially parallel tosaid second material conveyor; wherein said tank includes an upperchamber and a lower chamber, said first material conveyor and saidsecond material conveyor each having at least a lower end disposed insaid flocculent within said upper chamber, said tank includes apartition dividing said upper chamber from said lower chamber, saidpartition defining an opening placing said upper chamber and said lowerchamber in fluid communication; and further including a valve disposedin said opening.